The objective is to elucidate spectroscopically the mechanisms used by four different biochemical systems (ferrochelatase enzyme, catalytic DNA, catalytic RNA, and catalytic antibodies) for insertion of metal ions into porphyrins. Understanding these mechanisms should provide better insight into erythropoietic protoporphyria, a disease resulting from inactivation of ferrochelatase. Laser excitation within an electronic transition of a molecule gives rise to enhanced Raman scattering from selected vibrational modes. By comparing the resonance Raman spectra of solutions containing only porphyrin with solutions containing porphyrin bound to one of the four catalysts, structural distortions of the porphyrin induced by the catalyst may be identified. Subsequent analysis of the Raman scattering intensities using a combination of ground state vibrational force fields, structural calculations on the excited state, and resonance Raman transform theory will yield quantitative values for the local mode distortions induced by the catalysts. Different mutants and strains of the ferrochelatase enzyme will be prepared and studied to determine which amino acid residues are responsible for substrate distortion and to elucidate the nature of the Fe-S cluster found in mammalian strains of the enzyme. Catalytic antibodies with varying degrees of activity will be examined to determine if the extent of structural distortion can be directly correlated with activity.